Atrial fibrillation (AF) conveys profound morbidity and mortality and is principally a disease of advanced age. Subclinical AF results in debilitating outcomes in older adults. There has been markedly limited study of the relation of AF to physical performance and functional status, established metrics of adverse age-related decline. Our central hypothesis is that AF contributes significantly to declining physical performance and functional status in older adults. Our long-term goals are two-fold: to examine how AF exacerbates functional limitations, and ultimately to determine if earlier identification of subclinical AF can mitigate its impact on such processes. The present investigations will examine the cross-sectional and prospective relations of AF to functional assessments in the biracial Health, Aging, and Body Composition (Health ABC) Study, consisting in 3,075 well-functioning older adults (70-79 years). As a complementary aim, the investigations will develop an innovative pilot and feasibility study examining subclinical AF in a cohort of home-bound older adults selected from the Boston University Geriatrics Home-Care Program (mean age 84.2, 54% African American). Aim 1 will examine the cross-sectional relations of AF to physical performance and functional status in Health ABC at the baseline exam and years 4, 6, 8 and 10. Aim 2 will determine the prospective relation of AF to longitudinal changes in measures of physical performance and functional status across Health ABC exams. Aim 3 will employ an unobtrusive 7-day cardiac rhythm monitor in home-bound older adults (n=100), establishing pilot and feasibility data for detection of subclinical AF. The proposed studies will fill important gaps in AF and geriatric epidemiology. Determining the relation of AF to age-related decline in physical performance and functional status has important implications for earlier detection and treatment of AF to prevent such decline. Detecting subclinical AF in home-bound, frail older adults may prompt evidence-based interventions (i.e. stroke prevention) that reduce the severe morbidity associated with AF. These investigations will contribute towards an expanded study to examine the prevalence of subclinical AF in a larger cohort of home-bound older adults and determine its prospective relation to adverse outcomes. Key mentoring in geriatric research and AF and integration in the Boston Claude Pepper Older Americans Independence Center will enhance the proposed investigations. 9/27/2012